Device for scanning a panel



Jan. 3,

Filed July 15, 1958 G. DIEMER ET AL DEVICE FOR SCANNING A PANEL 2 Sheets-Sheet 1 NVENTOR I SINUS DIEMER f O HA Ny RIT VAN SANTEN anwl l NES SCHOENMAKEK AGE Jan. 3, 1961 cs. DIEMER ETAL 2,967,265

DEVICE FOR scmmmc A PANEL Filed July 15, 1958 2 Sheets-Sheet 2 P2 7 qlps I 1 FT INVENTOR GESINUS DIEMER JOHANNE GERRIT VAN SANTEN SIMON DUINKER WIJNAbEYJOHANNES SCHOENMA KERS AGENT United States atet DEVICE FOR CG A PANEL Gesinus Diemer, Johannes Gerrit van Santen, Simon Duinker, and Wijnand Johannes Schoenrnakers, all of Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed July 15, 1958, Ser. No. 748,752

Claims priority, application Netherlands July 15, 1957 17 Claims. (Cl. 315-169) The invention relates to a device for scanning a panel consisting of two or more intercoupled groups of conductors, the device being connected to a group or to part of a group of conductors.

Such scanning devices may, for example, be used for scanning a reproducing or display panel provided with electro-luminescent substances for the reproduction of a televisionor radar-image.

In this case voltages of sutficient value and having adequate information for the image to be reproduced must be applied to very closely adjacent conductors of a group. Since these voltages are coming in as a function of time, they must be supplied in order of succession to different conductors of a group. This gives rise to the difiiculty that the parasitic capacities occurring between the very closely adjacent, long conductors are a source of trouble for scanning.

The device according to the invention provides a solution for these difficulties and is characterized in that it comprises asystem with a delay circuit which is connected via a plurality of tappings to the series combinations of unidirectionally conductive elements and elements which are added to the former and which are capable of emitting radiation or extinguishing under the action of ap plied voltages, and a system comprising photo-conductive elements which are electrically coupled with the said conductors of the panel, the two systems being electrically separated from each other as far as possible and located relatively to each other in a manner such that the radiation from the radiating or extinguishing elements acts upon the added photo-conductive elements, while the ends of the series combinations not connected to the said tappings are connected to a source of pulsatory voltages and each of the photo-conductive elements is included in an electrically energized circuit.

A second, modified embodiment is characterized in that in the last-mentioned system on the side of the tappings the layer of photo-conductive elements has applied to it, in addition, a second layer containing fixed resistance elements, on which layer is provided a fixed electrode which last mentioned one is connected to a source of alternating voltage.

One embodiment of such a device for scanning a panel for the reproduction of a televisionor radar image will be described more fully with reference to the accompanying drawings, in which:

Fig. 1 shows a reproducing panel with the associated scanning apparatus.

Fig. 2 is a detailed view of the device shown in Fig. 1 according to the invention.

Fig. 3 shows a partial electrical circuit diagram of the device shown in Fig. 2.

Fig. 4 shows characteristic curves to explain the invention.

Fig. 5 is an equivalent circuit diagram of the arrangement shown in Fig. 3.

Fig. 6 shows a modification of the device shown in F g- 2 EQQ Fig. 7 is an equivalent circuit diagram of the arrangement shown in Fig. 6.

Fig. 1 shows a reproducing panel comprising a group of conductors a -a and a group of conductors b -b Such a reproducing panel may be provided, for example, with an electro-luminescent layer and unidirectionally current-conveying elements, as is described in a concurrently-ilcd, copending U.S.A. patent appication Serial No. 748,751.

The required signals for the vertical conductors b l1 are obtained from the device 1, which comprises a tapped delay circuit 2, a first electrode 3, which is pervious to radiation and to which a pulsatory voltage V from .a voltage source 7 can be supplied, a second electrode 3', which is pervious to radiation and which is connected to earth, and a third electrode 4, to which an alternating voltage V- from the voltage source 8 is supplied.

Via the contacts 5 the signals are obtained from th device 1 and supplied to the conductors b b To the horizontal conductors a a are supplied, from the device 23, the required voltages, as will be evident from the following.

The operation of the device 1 will be described with reference to the detailed View of Fig. 2, as an example, for television purposes. It will be obvious that such a device may also be used for other purposes.

When used for television purposes, the total video signal V is applied to the delay circuit 2. The time-delay produced by this delay circuit must be such that a signal V applied at 20 requires just one line period to travel from 20 to 21. If it is assumed that the system used has an image composed of 625 lines, while 25 images are transferred per second, the line period is m -64: uses.

If it is furthermore assumed that the delay circuit produces a time-delay of for example 10 ,usec/metre, a cable of about 6.4 m. of length must be used; this cable can be accommodated in zigzag or wound form below the reproducing panel. The delay circuit 2 is closed by its characteristic impedance Z in order to present reflections at the end of the cable.

It should be noted here that, in principle, any delay circuit may be employed, for example an acoustical circuit, in which case first the electrical signals are converted into acoustical signals, which are subsequently converted at the tappings into electrical signals. Use could be made, for example, of piezo-electric or piezo-magnetic elements. For the sake of simplicity, only an electrical delay circuit is described herein.

Such a delay circuit may be formed by winding a wire, such as copper wire or the like, on a longitudinally stretched round bar which is made of isolating material, for example, ferrite with an E,- of about 20 and an ,u, of about 100.

The delay circuit 2 has N equidistant tappings, so that the circuit is divided into Nl sections, each of which must have a delay time equal to the time of one image point. If, for the sake of simplicity, 640 image points per line are assumed, the delay time per section must be about 0.1 nsec.

It will be obvious that, if the delay circuit 2 were directly connected to the reproducing panel, i.e. directly to the contacts 5 of the conductors b -b each section of the delay circuit 2 would be shunted by a parasitic capacity 13, which is shown in Fig. 1. These capacitances have a value of about a few tenths of a pF and 3 the sections for the very high video frequencies would be short-circuited, so that there would no longer be any delay.

in order to avoid this, layers with associated auxiliary electrodes are sandwiched between the contacts and the tappings b' and b on the delay circuit 2, so that the circuit 2 is screened electrically from the contacts 5 and the information is yet transferred, subsequent to transformation, from the circuit 2 to the conductors of group b. It should be noted here that the term layers is to be understood to mean herein the elements of one kind united in one layer, while, if necessary, various layers of this kind may coincide geometrically, so that different elements are then united in one geometrical layer.

In order of succession are provided the layers 15, 16, 26, 18 and 19, the metal islands 17 of the largest possible dimensions, the first electrode 3 pervious to radiation, the second electrode 3' also pervious to radiation and the third electrode 4.

The layer 15 comprises unidirectionally conductive elements. These elements may be obtained by applying a p-n-junction to an insulating mass at discreet, equidistant points corresponding to the tappings of the delay circuit 2. The p-n transition may, for example, be obtained with the aid of a germanium or silicon.

A further possibility consists in the application of a light-sensitive, unidirectionally conductive layer (herein light is to be understood to include both visible and invisible light), which may be composed, for example, of a composition made of 84% cadmium sulphide and 16% silicate compound, and which is rendered unidirectionally conductive with the aid of a forming direct voltage and which is exposed at the tappings, so that it is operative only at thesepoints and conduction between the tappings is avoided, since the dark resistance ohm-cm.

When this light-sensitive layer is used, provision must, of course, be made of an opaque layer, for example a lacquer layer, sandwiched between the layers and 16, so that no light from the source of light can penetrate into the further layers and, conversely, no radiation can penetrate from the layer 16 into the layer 15. Particularly for large reproducing panels, with which the delay circuit 2 need not be wound, these light-sensitive layers are important.

The metal islands 17 are provided to establish a connection between the unidirectionally conductive elements of the layer 15 and the electro-luminescing elements of the layer 16. The latter elements, which may be made, for example, from manganese (1000 p.p.m.) or chlorine, manganese (1000 p.p.m.) activated zinc sulphide or other phosphor compounds, are, if necessary, surrounded by an insulating mass and emit light as soon as an adequate voltage prevails between the auxiliary electrodes 17 and the transparent electrode 3 which contacts these electroluminescent elements as shown. The layer 26 is a galvano-insulating layer, which must, however, be transparent in order to allow the light produced by the elements of layer 16 to pass to the elements of layer 18. To this end use may, for example, be made of a glass layer or an opaque, galvano-insulating substance, in which apertures are provided at the desired points, these apertures being filled, if required, with a galvano-insulating substance to allow the light to pass. The layer 18 comprises photo-conductive resistance elements, which may be composed, for example, of a composition made of 50% activated cadmium-sulphide with 50% cadmium selenide compound (CdS, CdSe). Also in this case the photo-conductive material in insulating material is applied at discreet, equidistant points opposite the tappings b b of circuit 2. A photoconductive substance is to be understood to mean a substance, of which the specific resistivity or impedance can be reversibly changed or varied by corpuscular or electro-magnetic radiation.

The layer 19 comprises conventional resistance elements, which are also embedded in insulating material opposite the photo-conductive elements of the layer 18. Between each of the elements of the layers 18 and 19 provision is made of tappings b "b which lead to the contacts 5. The layers 15, 16, 26, 18 and 19 can, for example, be constructed as follows.

Thin coatings of tin oxide or indium oxide, alloyed with about /z% of antimony are firmly connected onto opposite sides of a glass plate, forming the galvanoinsulating layer 26, by means of a spraying technique. These coatings form respectively the thin transparent electrodes 3 and 3'.

Thereafter the electroluminescent layer 16, with a thickness of about 20 is formed on the electrode 3 by means of a screening process.

Printing techniques are used for printing the electrodes 17 on the layer 16, whereas thep-n layer 15, with a thickness of about is an evaporated layer. Also a printing technique is used to fit the tappings b 'b onto the layer 15.

The photo-conductive layer 18 should have a thickness of about 200 and can be mounted on the coating 3' by means of a spraying or screening technique. It should be noted, that it must be able for the light, produced by the electro-luminescent elements of the layer 16, to penetrate easily into the layer 18 for varying the conductivity of the latter. For this purpose the layer 18 may be formed in the same manner as is done in the case of an amplification (see for example P.I.R ,E., vol 43, No. 12, December 1955, pages 1888 1897).

The tappings 5 can be formed by means of a printing technique, whereas the connection of the layer 19 and the transparent electrode 4, if necessary, can be accomplished by means of a spraying process or the like. Electrode 4 can be made of the same materials as the electrodes 3 and 3'. All these layers, together with the delay circuit2, whichtappings are connected to the tappings b '-b of the layer 15, are mounted in a; box. Thereafter the whole device is ready for cooperation with the reproducing panel The signal V which is supplied to the delay circuit 2 with a total time lag of 64 ,usec., therefore requires just one line period to travel from the input 20 to the output 21. Since there are 640 image points and 640 tappings and since each section has a time lag of 0.1 ,usee, the correct video information for each image pointis at one of the associated tappings-b 'b after 64 psec. If the signal V is supplied with positive polarityand negative-going synchronizing pulses, a voltage pattern is obtained along the circuit 2, which pattern renders each of the points'b 'b more or less positive to earth.

At any instant, when the information is distributed correctly along the delay circuit 2, i.e. after each period of 64 ,usec., a short-duration, positive pulse V is supplied from the voltage source 7 to the electrode 3. Thus the electrode 3 is, for very short intermittent instants, at positive potential and during the remaining time at earth potential. The maximum value of this pulse must exceed the maximum positive value prevailing along the circuit 2. This is illustrated in Fig. 3, which shows the substitute diagram of the device shown in Fig. 2 for-a few tappings b b and b, In this figure, in which corresponding parts are designated by-thesame references, all elements of the layers 15, 16, 18 and 19 are shown-as separate elements. The electrode 3 is connected to earth via the voltage source 7 and the positive potential of the electrode 3 during the short instant is indicated by V The various voltages along the circuit 2 are indicated by V V and V so that always V V V V and V V The unidirectionally conductive elements 15 are cutoff as long as the electrode 3 is at earth potential. Only at the instant when the electrode 3 is at V the elements 15 will convey current, so that the elements 16 can emit emit light and this with the greater intensity the higher is the potential difference between Vp2++ and V If it is assumed that V i designates the blacklevel, the potential difference between Vp2++ and V is high and the associated element 16 of the branch b, will emit light more strongly than that of the branch k in which V designates the white level.

The light from the elements 16 penetrates through the transparent electrodes 3 and 3' onto the associated photoconductive elements of the layer 18, so that the mean resistance value of these elements will decrease in accordance with the greater intensity of the light emitted by the elements 16. The element 16 of branch b emits light with great intensity, so that the resistance of the element 18 of branch b, is, on an average, smaller than the resistance of the element 18 of branch b since the associated element 16 emits light of less intensity.

It should be noted here that both the emitting of light by the elements 16 and the reaction of the photo-conductive elements 18 are attended with a certain degree of inertia. In Fig. 4a the positive pulse V in Fig. 4b the luminous flux Q5 (Lumen/m?) supplied by an element 16, and in Fig. 4c the conduction G of an element 18, irradiated by the luminous flux of the associated element 16, are shown as functions of time.

The elements of the layer 16 emit light and attain a maximum intensity at the instant when V returns to zero, after which the luminous flux decreases exponentially. The conduction G is at the same instant at its maximum and also decreases exponentially, so that the mean conduction of the elements 18 varies with the intensity of the light emitted by the elements 16. The inertia of the elements 16 and 18 must be such that the phenomenon terminates at the occurrence of the nextfollowing pulse V The application of the insulating layer 26 provides a complete electric insulation of the portion on the righthand side of the electrode 3' (Fig. 3) from the portion on the left-hand side of the electrode 3, so that the effect of the parasitic capacities 13 on the delay circuit 2 is obviated.

From the foregoing it is evident that the variableimpedance elements 18 in the various branches b "-b vary with the voltages V at the tappings b 'b Then an alternating voltage V- with a frequency chosen particularly for this purpose is supplied to the electrode 4 from the panel voltage source 8. The frequency of, V- must exceed but it must be lower than the maximum video frequency, since this voltage V-, as will be explained more fully hereinafter, serves only to cause the electro-luminescent layer of the reproducing panel to radiate in accordance with the values of the various resistances 18. If, for example, this voltage V- has a frequency lying between 50 and 150 kc./s., for example 100 kc./s., this voltage V- is operative between two pulses V 2, occurring 64 sec. one after the other, for a few periods.

This may be evident from Fig. 5. This figure, in which corersponding parts are designated by the same references, shows a partial equivalent circuit diagram of the device shown in Fig. 3 for the branches b b and b and moreover the elements 22 and the conductor (i The elements 22 contain the part of the electroluminescent layer and the biassed, unidirectionally conductive element associated wtih the crossings of the conductors b b and [n with the conductor a; of the reproducing panel as described in the aforementioned copending application. It is assumed that the device 23 of Fig. 1 causes, in succession, the conductors a e to be at earth potential for one line period. As said above, the image information V associated with the line a; is supplied to the delay circuit 2, so that the resistance value of the elements 18 corersponds to the information per image point on the line 11,. The voltage V- from the voltage source 8 is divided for each crossing into a voltage across the invariable or fixed resistance 19 and a voltage across the resistance 18, if care is taken that always the impedance of the element 22 is high relative to that of the element 18. Across each element 22 is then produced such an alternating voltage that each element 22 will radiate in accordance with the intensity of the supplied video signal V It is thus set out in the foregoing that the mean value of the resistance 18 in branch b," is smaller than that in branch b The voltage across the element 22 in branch b, will therefore be smaller, on an average, than that across the element 22 in branch b1+2 so that the first element will not radiate, whereas the second element will radiate, which radiation corresponds to the image information initially supplied to the delay circuit 2. 1

If the values of the resistances 19 and also the frequency of V- are chosen such that the impedance of a parasitic capacity 13 is high with respect to the value of a resistance '19 for the frequency of the AC. voltage delivered by the panel source 8, the influence of the parasitic capacity 13 will be negligible.

After the pulse V has been supplied, the signal associated with the line a, can leak away via the surge impedance Z of circuit 2, while at the same time the source 6 supplies the video information for the line a to the circuit 2. At the desired instant, the source 7 transfers the pulse V to the electrode 3' and the cycle is repeated for the crossings associated with the conductor a which is connected to earth by the device 23.

It should be noted that a satisfactory operation requires that for the time when one of the conductors of the group a, for example the conductor a is connected to earth, all other conductors of this group (a a and aimn) Should be at a direct voltage V,, so that all unidirectionally conductive elements of the reproducing panel are cut off at the undesired crossings. If

then radiation of the undesired crossings will be avoided, since the unidirectionally conductive elements in layer 22 provide that the current can flow only in the direction of the conductors b to the conductors a and not conversely.

The circuit arrangement 23 is shown only diagrammatically in Fig. 1. This arrangement comprises a switch 9, which connects, in order of succession, the contacts 25 of the conductors a a to earth for one line period. These contacts 25 are furthermore connected via large resistors 10 to the voltage source 11, which supplies the voltage V,,. In the drawing the conductor a for example, is connected to earth; the resistance 10 of this conductor provides that the voltage at all further conductors remains equal to V,,'. Owing to the low switching frequency of about 15 kc./s., the parasitic capacities 14, also prevailing in this case, will have little troublesome effect.

In a simple manner interlacing may be obtained in this case by causing the switch 9 to scan first the oddnurnbered lines a a a and subsequently the evennumbered lines a a a Then the source 6 supplies a video signal composed in accordance with the method of interlacing. A practical embodiment of the scanning device 23 may be obtained by replacing the switch 9, for example, by two switching tubes, having an adequate number of anodes; to this end usemay, for example; be made of cathode ray tubes. If n is equal to 625, the 625 horizontal conductors may be divided, by a known method, into two closely-adjacent conductors each, so that two groups of 625 conductors are formed, which are divided each into 25 groups of 25 conductors.

All 25 conductors of each of the 25 groups of the first group of 625 conductors are interconnected, if necessary 7 with the aid of intermediate resistors, and each group is connected to one anode of the first cathode ray tube, which must'be provided for this purpose with 25 anodes.

All first conductors of each of the 25 groups of the second group of 625 conductors are interconnected, all second conductors are interconnected, all third conductors are interconnected'and-so on, and each interconnection is connected to one of the'anodes of theisecond cathode ray tube, which is also provided with 25 anodes.

By controlling correctly the electron beams of the two cathode ray tubes with the aid. of control-pulses, the desired two adjacent conductors, for example at the area of the line designated by a can be caused to assume such a potential that the correct potential distribution prevails in the associated elements of the reproducing panel.

In order to minimize the attenuation and the distortion ofthe delay circuit 2, the arrangement 1 may be divided into two or more portions. During the scanning of one line, the source- 6 is then switched over from one portion to the other of the divided arrangement.

It will be obvious that even an opposite control. is possible. This is indicated in Figs. 6 and 7, which show equivalent diagrams corresponding to those of Figs. 3 and 5. The resistance layer 19 and the electrode 4 are omitted, the unidirectionally conductive elements of the layer 15 are reversed, and voltage source 7 holds the electrode 3 always at a potential V V so that the elements 15 are cut off, with the exception of the instants when the desired voltage pattern prevails along the delay circuit 2. At these instants the electrode 3 is at earth potential for a short time'and the elements 15 are no longer cut off, so that the elements 16 radiate in accordance with the voltage pattern along circuit 2. It is again assumed that V designates the black level; then the element 16 of the branch b, will. not radiate and the element 16 of the branch b, '.will radiate strongly owing to the fact that V designates the white level. The resistance 18 of the branch b," will then, on an average, exceed considerably the resistance 18 of the branch b If the panel voltage source 8 is connected on the one hand to the electrode 3' and on the other hand to earth, the equivalent diagram shown in Fig. 7 is obtained, when the device 2-3 connects the conductor to earth for one line period. On-an average, a low alternating voltage will prevail across the panel element 22 of the branch b and a high alternating voltage across the element 22 of the branch 'bi+2 The first-mentioned element 22 will not radiate, the second element, however, will. The insulationand also the capacity between the electrodes 3' and 3 must be such that'relative influence is avoided. In the first-mentioned control-method this is less critical, since in this case the electrode 3 is not at earth potential only for short instants, whereas the electrode 3' is constantly connected to earth. The second method has the advantage, however, that with the occurrence of the black level the non-radiation of the element 22 concerned can be better controlled.

If the signal V is supplied with negative polarity, also V must have negative polarity, while the unidirectionally conductive elements 15 must be reversed both in the first and in the second embodiment.

It will, moreover, be obvious that, if the supplied television signal has positive polarity, but is applied with positive-going synchronizing pulses to the delay circuit, the arrangement shown in Fig. 6 can be employed; in this case, however, the electrode 3 assumes a high potential owing to the voltage source 7 each time for a short instant and earth potential for the remaining time, while furthermore the elements IS'must be reversed. If in this case the arrangement shown in Fig. 3 is to be used, the unidirectionally conductive elements and the direction of the pulse V must also be reversed. a

'If use is to be made of elements 16 which emit light under the action of a. radiation from an additionalsource of radiation, but which extinguish to a greater or smaller amazes 8 extent under the action of applied voltages, a suitable combination of the arrangements shown in Figs. 3 and. 6 may be used; in this case the signal to be supplied to the delay circuit may have positive or negative polarity in accordance with the prevailing conditions.

.Toproduce a three-colour television system each of the conductors of group b, for example, may be divided into vthreeconductors. At the three crossings, thus formed at one initial crossing, three different electroluminescent substances are provided, each of them emitting light in a different colour.

The group of conductors a remains unchanged and can be controlled in the known manner. The group of conductors b is divided into groups b, b" and b'. Each of these groups can be connected to an arrangement 1 as shown in Fig.2. To each of these three arrangements is supplied a signal V of the corresponding subscript, where V designates, for example the red, V the blue and V the green signal. It will be obvious that more or fewer colours can be rendered visible in this manner by dividing the number of conductors of group b in a corresponding manner.

The embodiments shown herein relate to the scanning of a reproducingpanel to reproduce television images. The arrangement 1 may, however, be used for other purposes, for example for a large memory panel, in which the information is supplied in order of succession to the circuitZ and can be read as a whole per line.

.What is claimed is:

1. A display panel of the type comprising plural voltage-responsive means for displaying the information present in a time-varying video signal containing image informationrecurn'ng in consecutive scanning intervals, and including means for receiving said time-varying video signal and converting the image information in a scanning interval into plural space-displaced voltages, and means coupling the signal-receiving. means to the voltage-responsive means for simultaneously transferring said plural voltagescorresponding to the video information for a scanning interval to plural voltage-responsive means once during each scanning interval.

2. A display panelas claimed in claim 1 wherein the transferring means include voltage-responsive elements.

3. A display panel of the type comprising crossed groups of parallel conductors and means for energizing same to display information present in a time-varying video signal, comprising a plural-tapped delay circuit, means for introducing into the delay circuit a video signal containing image information recurring in consecutive scanning intervals, normally non-conducting, voltageresponsive means coupling each conductor of a groupto a tapped portion of the 'delay circuit, and means for periodically pulsing all ofsaid last-named means simultaneously once during each scanning interval thereby to transfer simultaneously to the conductors the information then existent as voltages along the tapped portions of the delay circuit.

4. A display panel of the type comprising crossed groups of parallel conductors and means for energizing same to display information present in a time-varying video signal, comprising a plural-tapped delay circuit, means for introducing into the delay circuit a videosignal containing image information recurring in consecutive scanning intervals, normally non-conducting voltageresponsive means, electro-luminescent means and photoconductive means optically coupled to the electro-lumines cent means coupling each conductor of a group to a tapped portion of the delay circuit, and means for periodically voltage-pulsing all of said voltage-responsive means simultaneously once during each scanning interval thereby to render them conductive and transfer simultaneously to the conductors the information then existent as voltages alongthe tapped portions of the delay cir cuit.

5. A display panel of the type comprising crossed groups of parallel conductors and means for exciting same, said exciting means comprising a signal-receiving and radiation-producing system electrically separated from but optically coupled to a panel energizing system; said signal-receiving system comprising a plural-tapped delay circuit for receiving a time-varying video signal and distributing it along its length to convert it to spacedisplaced voltages at the taps, voltage-responsive radiating elements coupled to each tapped portion of the delay circuit, and means for periodically energizing the lastnamed elements to cause the radiating elements to generate radiation in response to their applied voltages; said panel-energizing system comprising radiation-responsive elements each associated with and only responsive to the radiation generated by one radiating element, and a source of panel-energizing voltage; and means coupling each of the conductors of one of said groups through the radiation-responsive elements to the panel-energizing source.

6. A display panel of the type comprising crossed groups of parallel conductors and means for exciting same; said exciting means comprising a signal-receiving and radiation-producing system electrically separated from but optically coupled to a panel-energizing system; said signal-receiving system comprising a plural-tapped delay circuit for receiving a time-varying video signal and distributing it along its length to convert it to space-displaced voltages at the taps, series-connected unidirectionally-conductive and voltage-responsive radiating elements coupled to each tapped portion of the delay circuit, and means for periodically pulsing the said series-connected elements to cause the radiating elements to generate radiation in response to their applied voltages; said panel-energizing system comprising radiationresponsive, variable-impedance elements each associaied with and only responsive to the radiation generated by one radiating element, and means for applying a panelenergizing voltage to each of the variable-impedance elements; and means coupling each of the conductors of one of said groups to a variable-impedance element, whereby the voltage applied to the conductor is con trolled by the variable impedance element whose impedance is in turn controlled by the associated radiating element whose radiation is in turn controlled by the voltage derived from the time-varying video signal and existent at the associated tapped portion of the delay circuit at the time the pulse is applied.

7. A display panel of the type comprising crossed groups of parallel conductors and means for exciting same, said exciting means comprising a signal-receiving and radiation-producing system electrically separated from but optically coupled to a panel energizing system; said signal-receiving system comprising a characteristicimpedance-terminated plural-tapped delay circuit for receiving a time-varying video signal and distributing it along its length to convert it to space-displaced voltages at the taps, adjacent layers forming series-connected unidirectionally-conductive and voltage-responsive electroluminescent radiating elements coupled to each tapped portion of the delay circuit, and means for periodically voltage-pulsing the said series-connected elements to cause the radiating elements to generate radiation in response to their applied voltages; said panel-energizing I system comprising a layer forming radiation-responsive, variable-impedance elements each associated with and only responsive to the radiation generated by one radiating element, and means for applying an alternating current panel-energizing voltage to each of the variableimpedance elements; and means coupling each of the conductors of one of said groups to a variable-impedance element, whereby the alternating-current voltage applied to the conductor is controlled by the variable-impedance element whose impedance is in turn controlled by the associated radiating element whose radiation is in turn controlled by the voltage derived from the time-varying 10 video signal and existent at the associated tapped portion of the delay circuit at the time the pulse is applied.

8. A panel as set forth in claim 7 wherein the panelenergizing source has a frequency between 50 and kilocycles/second, and the video signal is a television video signal.

9. An electrical device for receiving sequential information and delivering it in simultaneous form, comprising a plural-tapped delay circuit including input means for receiving the sequential information, a unidirectionally-conductive element and voltage-responsive radiator connected in series with each tapped portion of the delay circuit, means for applying a pulsatory voltage simultaneously to all the series-connected unidirectionally-conductive elements and voltage-responsive radiators of such a polarity to cause the unilaterally-conductive elements to conduct and causing the voltage-responsive radiators to radiate in accordance with the potential difference between the voltage at the associated delay circuit tap and the pulsatory voltage, a radiation-responsive, variableimpedance element optically associated with each radiator, means for applying an exciting potential to the variable-impedance elements, and means for deriving a signal voltage related to the exciting potential but modified by the value of impedance assumed by the variable-impedance element in response to the radiation from the associated radiator.

10. A device as set forth in claim 9 wherein the unidirectionally-conductive elements are constituted of a material selected from the group consisting of germanium and silicon and containing a p-n junction.

11. A device as set forth in claim 9 wherein the unidirectionally-conductive elements are constituted of cadmium sulphide and a silicate compound.

12. A device as set forth in claim 9 wherein the voltage-responsive radiator is a manganese-activated zinc sul phide electro-luminescent material.

13. A device as set forth in claim 9 wherein the variable-impedance elements are constituted of a photo-conductive cadimum sulpho-selenide compound.

14. An electrical device for receiving sequential information and delivering it in simultaneous form, comprising a characteristic-impedance-termina'ted plural-tapped delay circuit including input means for receiving the sequential information, a first layer containing unidirectionally-conductive elements each connected to a tap of the delay circuit, and a second layer containing voltageresponsive electro-luminescent elements, plural conductive islands each connecting in series a unidirectionallyconductive element and an electro-luminescent element, a first radiation-transparent electrode contacting all the electro-luminescent elements on the side opposite the islands, means for applying a pulsatory voltage to the said first radiation-transparent electrode of such a polarity to cause the unilaterally-conductive elements to conduct and causing the voltage-responsive elements to radiate in accordance with the potential difference between the voltage at the associated delay circuit tap and the pulsatory voltage, an insulating layer on the first radiation-transparent electrode, a second radiation-transparent electrode on the insulating layer, a third layer containing photoconductive, variable-impedance elements on the second electrode, means for applying an alternating-current exciting potential to the variable-impedance elements, and plural contacts each to a side of a variable-impedance element remote from the said electrode for deriving a signal voltage related to the exciting potential but modified by the value of impedance assumed by the variableimpedance element in response to the radiation from the associated electro-luminescent element.

15. A device as set forth in claim 14 wherein the insulating layer comprises an opaque member having transparent areas located between the associated electro-lumi nescent and photo-conductive elements.

16. A device as set forth in claim 14 wherein a fourth layer containing fixed-resistance elements is provided over the third layer with the elements contacting, the contacts, and a third continuous electrode is on the fourth layer and contacts all the fixed-resistance elements, said exciting potential being applied to the said third electrode.

17.. A device as set forth in claim 14 wherein a video signal is applied to the delay circuit input means, said video signal containing image information recurring in consecutive scanning intervals, the pulsatory voltage is and 15 0? kilocy cle's/ second.

References Cited in the file of this patent applied only once at the end of each scanning interval, 10 2,851,634

UNITED STATES PATENTS Toulon June 26, 1951 Livingston Dec. 18, 1956 Peek Dec. 31', 1957 Kazan Sept. 9,.1958 

